In recent years, a 3D movie becomes a big trend in movie and broadcast fields.
Diverse method and factors are applied to help a watcher feel better 3D effects, among which a method of using a viewing time difference between two eyes is most important. A stereoscopic 3D technology and a multi-view 3D technology are developed with the aid of a technique of using a viewing time difference between two eyes.
The stereoscopic 3D technology is mainly applied to the current 3D moving pictures, which technology consists of a glasses method and a non-glasses method depending on whether or not a user wears glasses. The glasses-based method consists of a method of using a polarized glasses and a method of using a shuttered glasses. The non-glasses based method consists of a lenticular method of using a film which has a lot of perpendicular, intense wrinkles and a Parallax Barrie method of using a perpendicular shut-off line.
The procedures that a watcher feels 3D pictures will be described with reference to FIG. 1.
A creature including human being can recognize an object with spaced-apart two eyes as one object even though there is a retinal image disparity which occurs since two eyes spaced-apart about a nose watch the thing with a time difference, because different retinal corresponding points at the retinas of two eyes are recognized by a brain as one object. When a watcher watches one object O, the image of the object O is formed at a macula F which corresponds to the retina corresponding points of two eyes. However, the watcher recognizes the macula F recognized by each eye, as an imaginary viewing axis F″, which is called a common visual direction corresponding to a common viewing axis. The point A is far away from the object O, but it is positioned at the common visual direction F″. When viewing the object O, the point A is formed at the point “a”, which is a corresponding point of the retina, closer to the nose as compared to the point F, so the watcher recognizes that the point “a” is positioned at the father back portion than the object O. On the contrary, since the point B is closer than the object O, the image is formed at the point “b”, which is a corresponding point of the retina, closer to the nose than the point F, so the watcher recognizes that the point “b” is at the more forward side than the object O. When the image is formed at both the corresponding retinal points of two eyes, the watcher recognizes as one thing like a single vision and has the common viewing axis.
What a thing is recognized in 3D along with a depth is called a stereopsis. In the stereopsis, there are an image watched by the left eye and an image watched by the right eye, and both the images are integrated and recognized as one image. The procedure that the retinal images from both the eyes are integrated as one image via a certain neural procedure is called a sensory fusion. For a reliable fusion, the image watched by the left eye and the image watched by the right eye should be at least similar with each other. If very different images are formed at both the eyes, there might be a problem such as diplopia, superimposition, and retinal rivalry in which two images are alternately seen or a suppression in which only one image is formed, which results in a visual fatigue in a brain.
According to a research, when the conventional 2D moving picture is converted into a 3D moving picture, the amount of the data to be processed by the brain of the human being is increased by at least 4 times or 7 times which exceeds the summed numbers of the left images and the right images. In this case, the quality of the image is much better. When the huge amount of the moving pictures is converted, the watchers might feel a lot of eye fatigue due to the over load of sensory fusion such as dizziness, nausea, and headache.
In worse case, when watchers watch the poorly manufactured 3D moving pictures or watch a 3D moving picture having a lot of motions and a complicated scene, the watchers might feel headache, nausea or dizziness, not feeling a reliable 3D moving picture.
The aftereffects after watchers watch a 3D moving picture might be very different depending on individuals. For example, a person used to a more complicated 3D moving picture might have less aftereffects or small aftereffects, but a person not used to the same, he might have huge aftereffects.
The above aftereffects do not always occur when watching a 3D moving picture. Namely, such aftereffects might occur when watching a 2D image. When a watcher watches a moving picture recorded in a hand-held technique, the watcher might feel dizziness or headache.
The moving speed of a character in a 3D contents and a motion of a recording camera might not change, but the complexity of an image that a watcher can subjectively recognize, is controllable.